[MemProf] Update the declaration DISubprogram linkageName for clones (#149864)

Follow up to PR145385 to also update the linkageName on any separate
DISubprogram for the clone function declaration.

Author: teresajohnson

llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp

@@ -3998,6 +3998,24 @@ void IndexCallsiteContextGraph::updateCall(CallInfo &CallerCall,
   CI->Clones[CallerCall.cloneNo()] = CalleeFunc.cloneNo();
 }
 
+// Update the debug information attached to NewFunc to use the clone Name. Note
+// this needs to be done for both any existing DISubprogram for the definition,
+// as well as any separate declaration DISubprogram.
+static void updateSubprogramLinkageName(Function *NewFunc, StringRef Name) {
+  assert(Name == NewFunc->getName());
+  auto *SP = NewFunc->getSubprogram();
+  if (!SP)
+    return;
+  auto *MDName = MDString::get(NewFunc->getParent()->getContext(), Name);
+  SP->replaceLinkageName(MDName);
+  DISubprogram *Decl = SP->getDeclaration();
+  if (!Decl)
+    return;
+  TempDISubprogram NewDecl = Decl->clone();
+  NewDecl->replaceLinkageName(MDName);
+  SP->replaceDeclaration(MDNode::replaceWithUniqued(std::move(NewDecl)));
+}
+
 CallsiteContextGraph<ModuleCallsiteContextGraph, Function,
                      Instruction *>::FuncInfo
 ModuleCallsiteContextGraph::cloneFunctionForCallsite(
@@ -4009,9 +4027,7 @@ ModuleCallsiteContextGraph::cloneFunctionForCallsite(
   std::string Name = getMemProfFuncName(Func.func()->getName(), CloneNo);
   assert(!Func.func()->getParent()->getFunction(Name));
   NewFunc->setName(Name);
-  if (auto *SP = NewFunc->getSubprogram())
-    SP->replaceLinkageName(
-        MDString::get(NewFunc->getParent()->getContext(), Name));
+  updateSubprogramLinkageName(NewFunc, Name);
   for (auto &Inst : CallsWithMetadataInFunc) {
     // This map always has the initial version in it.
     assert(Inst.cloneNo() == 0);
@@ -4950,9 +4966,7 @@ static SmallVector<std::unique_ptr<ValueToValueMapTy>, 4> createFunctionClones(
       PrevF->eraseFromParent();
     } else
       NewF->setName(Name);
-    if (auto *SP = NewF->getSubprogram())
-      SP->replaceLinkageName(
-          MDString::get(NewF->getParent()->getContext(), Name));
+    updateSubprogramLinkageName(NewF, Name);
     ORE.emit(OptimizationRemark(DEBUG_TYPE, "MemprofClone", &F)
              << "created clone " << ore::NV("NewFunction", NewF));
 

llvm/test/ThinLTO/X86/memprof-basic.ll

@@ -143,13 +143,14 @@ attributes #0 = { noinline optnone }
 !12 = !{i64 789, i64 300}
 !13 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !14, producer: "clang version 21.0.0git ([email protected]:llvm/llvm-project.git e391301e0e4d9183fe06e69602e87b0bc889aeda)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
 !14 = !DIFile(filename: "basic.cc", directory: "", checksumkind: CSK_MD5, checksum: "8636c46e81402013b9d54e8307d2f149")
-!15 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !13)
+!15 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !13, declaration: !22)
 !16 = !DISubroutineType(types: !17)
 !17 = !{!18}
 !18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !19, size: 64)
 !19 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
 !20 = !{i32 7, !"Dwarf Version", i32 5}
 !21 = !{i32 2, !"Debug Info Version", i32 3}
+!22 = !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
 
 ; DUMP: CCG before cloning:
 ; DUMP: Callsite Context Graph:
@@ -321,7 +322,8 @@ attributes #0 = { noinline optnone }
 ; IR: attributes #[[NOTCOLD]] = { "memprof"="notcold" }
 ; IR: attributes #[[COLD]] = { "memprof"="cold" }
 ;; Make sure the clone's linkageName was updated.
-; IR: ![[SP]] = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1"
+; IR: ![[SP]] = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1", {{.*}} declaration: ![[SP2:[0-9]+]])
+; IR: ![[SP2]] = !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1"
 
 
 ; STATS: 1 memprof-context-disambiguation - Number of cold static allocations (possibly cloned)

llvm/test/Transforms/MemProfContextDisambiguation/basic.ll

@@ -121,13 +121,14 @@ attributes #6 = { builtin }
 !12 = !{i64 789, i64 300}
 !13 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !14, producer: "clang version 21.0.0git ([email protected]:llvm/llvm-project.git e391301e0e4d9183fe06e69602e87b0bc889aeda)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
 !14 = !DIFile(filename: "basic.cc", directory: "", checksumkind: CSK_MD5, checksum: "8636c46e81402013b9d54e8307d2f149")
-!15 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !13)
+!15 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !13, declaration: !22)
 !16 = !DISubroutineType(types: !17)
 !17 = !{!18}
 !18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !19, size: 64)
 !19 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
 !20 = !{i32 7, !"Dwarf Version", i32 5}
 !21 = !{i32 2, !"Debug Info Version", i32 3}
+!22 = !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
 
 ; DUMP: CCG before cloning:
 ; DUMP: Callsite Context Graph:
@@ -290,7 +291,8 @@ attributes #6 = { builtin }
 ; IR: attributes #[[NOTCOLD]] = { builtin "memprof"="notcold" }
 ; IR: attributes #[[COLD]] = { builtin "memprof"="cold" }
 ;; Make sure the clone's linkageName was updated.
-; IR: ![[SP]] = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1"
+; IR: ![[SP]] = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1", {{.*}} declaration: ![[SP2:[0-9]+]])
+; IR: ![[SP2]] = !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1"
 
 
 ; STATS: 1 memprof-context-disambiguation - Number of cold static allocations (possibly cloned)